Naslov
Isometries and Computability Structures

Autori
Iljazović, Zvonko

Izvornik
Journal of universal computer science (0948-695X) 16 (2010), 18; 2569-2596

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
computable metric space; computability structure; effective total boundedness; effective dispersion; effective compactness; isometry

Sažetak
We investigate the relationship between computable metric spaces (X, d, alpha) and (X, d, beta), where (X, d) is a given metric space. In the case of Euclidean space, alpha and beta are equivalent up to isometry, which does not hold in general. We introduce the notion of effectively dispersed metric space and we use it in the proof of the following result: if (X, d, alpha) is effectively totally bounded, then (X, d, beta) is also effectively totally bounded. This means that the property that a computable metric space is effectively totally bounded (and in particular effectively compact) depends only on the underlying metric space. In the final section of this paper we examine compact metric spaces (X, d) such that there are only finitely many isometries X->X. We prove that in this case a stronger result holds than the previous one: if (X, d, alpha) is effectively totally bounded, then alpha and beta are equivalent. Hence if (X, d, alpha) is effectively totally bounded, then (X, d) has a unique computability structure.

Izvorni jezik
Engleski

Znanstvena područja
Matematika

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